Texas Tech University climate scientist Katharine Hayhoe isn't a household name, but she's still a star.

She's an author, host of the PBS digital series Global Weirding, lead author on three national climate assessment and an expert reviewer for the Intergovernmental Panel on Climate Change. And on Friday, she was a speaker for three events at EarthX in Fair Park, an expo known as the world's largest environmental festival.

Hayhoe, who runs Texas Tech's Climate Science Center, is a professor and researcher. But, like astrophysicists Carl Sagan and Neil deGrasse Tyson, her national reputation has risen thanks to her skill at explaining complicated science to audiences outside academia.

Hayhoe's memorable personal background has also helped raise her profile. Texas' most prominent climate scientist is actually Canadian. And she's also an evangelical Christian married to a pastor, details not usually associated with university scientists.

Here's what Hayhoe had to say about important climate change issues, including how global warming affects deadly storms like Hurricane Harvey.

Reasons for pessimism

"Every time a new scientific study comes out these days, it seems as if the climate is changing faster or to a greater extent than we thought before. What we've learned recently is the Atlantic meridional [overturning] circulation has been measured to have slowed down by 15 percent over the century," Hayhoe said.

A second study — both were published in the prestigious journal Nature — suggested that the slowing could have been natural rather than due to human impact. Either way, climate change is expected to slow circulation going forward, which would disrupt the seafood industry and lead to increased sea level rise.

"There's new mechanisms now we understand by which Antarctica is disintegrating faster than we thought," Hayhoe said. "Sea level is rising twice as fast now as when the satellite records began 25 years ago.

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"When we look at the science, that's not where I find hope."

Reasons for optimism

"I find hope in seeing what people are doing: The fact that Morocco has just finished building the biggest solar farm in the world, the fact that here in Texas we got 18 percent of our electricity from wind last year, and we're well on our way to 25 percent," Hayhoe said.

She also recounted a recent trip to a Christian missions conference in California.

"I heard amazing stories, like about a young woman who started a pay-as-you-go solar power program in Sub-Saharan Africa to bring people electricity, who never had any type of electricity before, with an app on their smartphones that they could use to pay for it. She was doing it as part of a Christian mission program. If that's the way the world's changing, it gives me hope."

What climate change does and doesn't mean for hurricanes

In a driving rainstorm, a man heads back into the flooded Pearland Acres mobile home community to help rescue and save residents' belongings in rural Pearland last August.(Tom Fox / Tom Fox)

"I know we had a ton of hurricanes this past season. It was insane. But we are not seeing more frequent hurricanes. ... But there are at least six ways that hurricanes are being amplified or exacerbated by a changing climate.

"The first thing is there's more water vapor for those storms to pick up and dump on us. So rainfall rates associated with hurricanes are going up," Hayhoe said.

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"Hurricanes get their energy from warm ocean water, and the oceans are warming, too. So hurricanes are intensifying faster. ... They're also intensifying to a higher level. While we're seeing the same number of storms, we're seeing more category 3s and 4s and even 5s than we used to.

"We find that the storms are moving slower. ... The more slowly they move, the longer they sit over one place to dump [rain] on it and the bigger the impacts. And storms are also getting bigger. No surprise because they get energy from warm ocean water. And of course, sea level is rising, so there is more water for the storms to push ashore and flood the coasts."

Hayhoe also pointed to research estimating that the chance of a Hurricane Harvey-type storm is now 1 percent annually.

Why do people reject climate science?

"The number one reason why most people reject the science of climate change today has nothing to do with the actual science and everything to do with the perceived solutions. They perceive the proposed solutions to only be on one side of the political spectrum," Hayhoe said.

"Climate is changing. Humans are responsible. That is a fact. Now let's argue over what solutions are best for my particular ideology and values."

Reasons to care about climate change

A dead fish lay on the rocks of what used to be an underwater portion of the DeCordova Marina, as the effects of the drought could be seen at Lake Granbury in May 2014.(Louis DeLuca / Staff Photographer)

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"The reason we care about climate change is because it exacerbates the risks we already face naturally in the place where we live.

"Climate change takes the ways we are already vulnerable, and it exacerbates them or amplifies them. If we live in Miami, one of things we care the most about is sea level rise and coastal storms and hurricanes. The same in Houston.

"If we live in Dallas or West Texas, where I am, we care a lot about drought, but we also care about heavy rainfall because we get that, too."

Big-tent approach at EarthX

EarthX organizer Trammell S. Crow is both a Republican and environmentalist. And at his annual expo, he often invites politicians — mostly GOP — and businesses — mostly oil and gas — that conflict with traditional environmental thinking.

Hayhoe said she appreciates that big-tent approach.

"The greatest challenge we have is the fact that climate change has been labeled as an environmental issue. When we say environmental, people have this immediate mental image of somebody who hugs trees, wears Birkenstocks, eats granola and always votes liberal.

"The reality is that climate change is a human issue," Hayhoe said. "It's an economic issue. It's an issue of national security. It's an energy issue. It's a humanitarian issue. And yes, it is an environmental issue, too. We care about a changing climate because it affects all the other things that are already on our priority list."